Orders keep rolling in for the forthcoming Model 3 from The extraordinary response to the vehicle, which will not even be built until late next year, underscored the demand among consumers for a mass-market electric car that carries Tesla’s luxury-brand cachet. Tesla said in a blog post that the number of reservations corresponded to about $14 billion in future sales, and was a milestone in the company’s growth. “This has been a true grass-roots effort…